Make integration tests compile

[scrabsha]

I was lazy when writing initial integration tests. As the system worked on the initial AST, i never tried to make the whole thing compile. Now that we're using rustc, our tests must compile. That's what this PR does.

The test still don't pass, but at least they compile :)

Some additional clean-up in the test runner has been performed too.

[o0Ignition0o]

As a followup we might wanna change A B etc into "Type / Subtype" or something more explicit